JPH0448627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an inkjet recording device, and more particularly to an inkjet recording device that performs recording by ejecting ink droplets onto a recording medium according to recording information.

[Prior Art] Conventionally, it has been known that the recording quality (print density, dot shape after printing, etc.) of this type of recording apparatus is greatly influenced by the physical properties of the recording medium. Therefore, it is recommended to use paper recommended for inkjet printers, which is a type of special paper, in any recording device, and the current situation is that the desired print quality can be obtained when using this paper. be.

The recommended paper is the isotropic diffusion of the droplets printed on it.
Physical properties such as diffusion speed, adsorption speed, and reflection density are determined in detail, and when recording is performed by loading a light-transmitting recording medium such as film for an overhead projector (hereinafter referred to as OHP) into such a printer. Due to differences in the physical properties of the recording medium, the quality of the print may deteriorate significantly, or in severe cases, the print may not be fixed.
Therefore, attempts have been made to improve the fixing properties by surface-treating the OHP film and forming a thin film of gelatin or PVA on the surface layer.

However, improvements in fixation affect all OHPs.
The characteristics of the printing film have not been improved, and the printing density is low due to the fundamental difference in physical properties from plain paper, which will be described below.

That is, unlike paper, OHP film has low diffusivity (that is, the spread of dots is small), and improved fixing performance also means a decrease in the diffusivity of OHP film. Therefore, when such an OHP film is loaded into a conventional inkjet printer and recorded, the dot of each pixel becomes small, thereby reducing the printing density and resulting in a pale colored and blurred recording. That is, the second
As shown in the figure, in the case of OHP film, 1
The dot diameter 3 ejected onto the pixel area 1 is smaller than the dot diameter 2 in the case of plain paper illustrated in FIG.

Furthermore, OHP films transmit light, while conventional recording paper uses the reflected light to express images, so even ink with relatively low ink density can be colored throughout (the dots are diffused). Even if the reflection density and ink density are not so low, when viewing an object with wide dot spacing and small dot diameter using transmitted light, the reflection density may seem higher.

There is a method of increasing the dye concentration in order to increase the printing density, but increasing the dye causes problems such as clogging if left for a long time and dye precipitation, so increasing the dye beyond a certain concentration causes problems such as clogging and dye precipitation. The problem is that I can't.

Another possible method is to eject ink multiple times to form one pixel to improve the recording density on OHP film, but on the other hand, when printing on plain paper, a large amount of ink is ejected, resulting in a decrease in resolution. This method causes problems such as ink leakage and wrinkles on the recording paper, and also has the disadvantage that the recording speed decreases because ejection is performed multiple times for each pixel.

[Objective] The present invention has been made in view of the above points, and its object is to provide an inkjet recording device capable of recording high-quality images at appropriate density on various recording media. Sometimes.

That is, the present invention provides an inkjet recording apparatus that records an image on a recording medium by moving a recording means that discharges ink droplets according to recording information relative to the recording medium in the main scanning direction and the sub-scanning direction. A signal generating means for generating a recording mode signal according to the recording medium, and a control means for controlling the number of main scans of the recording means for one pixel on the recording medium based on the recording mode signal generated from the signal generating means. The control means causes the recording means to main scan a pixel on the recording medium a first number of times based on a first recording mode signal, and during the first number of main scans, The ink droplet is ejected to one pixel the first number of times, and the ink droplet is ejected to one pixel on the recording medium a second number of times, which is greater than the first number of times, based on a second recording mode signal. Scanning is performed, and ink droplets are repeatedly ejected to one pixel for the second number of times during the second number of main scans, and one part of the ink droplet is ejected on the recording medium in the first printing mode and the second printing mode. An object of the present invention is to provide an inkjet recording device characterized in that the number of ink droplets forming pixels is different.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

In the third diagram, the reference numeral 11 indicates a paper guide, and the OHP film or recording paper 15 is carried along the roller 1 along this paper guide 11.
Sent in 7 directions. Further, a micro switch 13 is arranged along the paper guide 11, and the presence or absence of a recording medium is detected by this. Furthermore, a transmission type photo sensor 14 is arranged near the roller 17 with a paper guide in between, and this photo sensor 14 is activated when the recording medium is paper, and activated when the recording medium is light-transmissive such as an OHP film. The type of recording medium is determined based on whether the

Further, an inkjet unit 16 is disposed facing the platen 12, and discharges ink droplets according to recording information to record a dot image.

Further, the recording device according to the present invention has Y (yellow), M
Equipped with ink nozzles that can eject each color (magenta), C (cyan), and Black (black), and in normal scanning, that is, when recording on plain paper, each single color of Y, M, C, and Black can be ejected. When expressing, one dot is ejected per pixel according to the recording information, and when color is created by subtractive color mixing method such as R (ret), G (green), B (blue), etc. Recording is performed by injecting dots of the required color into each pixel one by one to develop the color.

On the other hand, when the photo sensor 14 detects an OHP film, the system is changed so that a larger number of dots than the number of dots normally formed per pixel are applied to each pixel. For example, for the same pixel of a single color, two dots of the same color are placed overlapping each other.
Discharge twice and perform double striking. This is done, for example, by recording dots from the opposite direction during the backward movement so as to overlap the printed dots during the forward movement, and then advancing the recording paper one line.

An arrangement implementing this method is illustrated in FIG. 4, in which the recording system is controlled by
An up/down counter 31 is connected to the CPU (central control unit) 30, and this counter
It counts up in synchronization with the clock from the CPU 30, and the data address corresponding to the counted value is determined via the address decoder 32. Record data 35 at that address from RAM (random access memory) 33 connected to external data 34
is read out in synchronization with the clock. In that case, the ejection position is checked based on the signal from the carriage position detection section 36, the driver 37 is driven, and the above-mentioned data 3 is sent via the inkjet unit (IJU) 38.
Dot recording according to step 5.

On the other hand, when returning, counter 31 is used as a down counter.
The number of counters 31 is reduced using , and the data is taken out in synchronization with the clock, contrary to the previous printing, and the return printing is performed. As a result, the same data can be entered twice. The same can be considered when multiple printing is performed. In this case, the data in the RAM 33 continues to be held until reciprocating printing is performed a predetermined number of times, and the paper is not fed by the paper feeding mechanism 41.

When reaching a certain value N (the number of overprints) initially set in the CPU 30, the RAM 33 is refreshed and takes in new data.
Perform the paper feed according to step 1 and move on to the next printing.

The operation of the device configured as described above is explained in the fifth section.
This will be explained with reference to the flowchart in the figure.

When normal recording paper is loaded, the recording paper 15 enters along the paper guide 11, operates the micro switch 13, and blocks the optical path of the photo sensor 14, allowing the system to operate normally. Thereafter, the inkjet unit 16 discharges one dot droplet per pixel to perform recording.

On the other hand, when an OHP film is loaded, the output of the photo sensor 14 is not affected because the film is transparent, and as described above, ink droplets are ejected multiple times to each pixel to perform recording.

That is, as shown in FIG.
1. At S2, the output from the micro switch 13 and the photo sensor 14 causes the program to proceed to a routine for recording on normal recording paper (step S3) or a routine for recording on OHP film (step S4). Further, if the output of the microswitch cannot be obtained, a warning is issued in step S5.

In this way, for OHP film, 1
The recording density per pixel is increased by increasing the amount of ink ejected and injected into the pixel. In this case, the dot diameter is also larger than in the case of one dot, approaching that when the recording medium is paper (this indicates that the space between the dots becomes narrower and the background portion decreases).

With such simple operations, a clear image with high recording density can be obtained even on OHP film, and a sufficiently good image can be obtained even when projected onto a screen using transmitted light.

In the embodiments described above, the photo sensor may be of a reflective type, or the positional relationship between the microswitch and the photo sensor may be other than the above.

Further, in order to improve the degree of contact between the recording medium and the platen, the recording medium may be suctioned by a negative pressure source. This example is illustrated in FIG. 6, in which the same parts as in FIG. 3 are given the same reference numerals, and their explanation will be omitted. In the figure, the recording medium 15 is sucked by a negative pressure source 20 and brought into close contact with the platen, thereby further improving the recording quality. Further, the negative pressure can be released by a release valve 18. Furthermore, a pressure sensor 19 is provided in the suction channel, and the negative pressure in the channel is detected by this. The generation of this negative pressure and the photo sensor 14
By combining the outputs of , a relationship equivalent to that of the micro switch and photo sensor described above can be obtained.

[Effects] As described above, according to the present invention, there are recording modes in which the number of ink droplets ejected to one pixel differs depending on the recording medium, and each recording mode performs main scanning a different number of times for one pixel on the recording medium. Since a different number of ink droplets are ejected depending on the type of recording medium, it is possible to record a high-quality image at an appropriate density regardless of the type of recording medium.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram when recording on plain paper.
Fig. 2 is an explanatory diagram when OHP film recording is performed, Fig. 3 is a side view showing the structure of the ink jet printing device, Fig. 4 is a block diagram showing the configuration for overlapping dots, and Fig. 5 is the operation. FIG. 6 is a side view showing another embodiment of the inkjet recording apparatus. 1... Pixel area, 2, 3... Dot diameter, 12...
...Platen, 13...Micro switch, 14...
... Photo sensor, 15 ... Recording medium, 16 ... Inkjet unit, 19 ... Pressure sensor, 2
0...Negative pressure source.

Claims (1)

[Scope of Claims] 1. An inkjet recording device that records an image on a recording medium by moving a recording means that discharges ink droplets according to recording information relative to the recording medium in the main scanning direction and the sub-scanning direction. A signal generating means for generating a recording mode signal according to the recording medium; and controlling the number of main scans of the recording means for one pixel on the recording medium based on the recording mode signal generated from the signal generating means. a control means, the control means causes the recording means to perform main scanning a first number of times for one pixel on a recording medium based on a first recording mode signal, and causes the main scanning of the first number of times The ink droplet is ejected the first number of times for one pixel during scanning, and the ink droplet is ejected a second number of times greater than the first number of times for one pixel on the recording medium based on a second recording mode signal. perform main scanning by means;
Ink that repeatedly ejects ink droplets to one pixel the second number of times during the second number of main scans, and forms one pixel on the recording medium in the first printing mode and the second printing mode. An inkjet recording device characterized by having different numbers of droplets.